Recently, portable data processing apparatuses, such as laptop personal computers, have been improved in terms of processing performance and have been made thinner. Therefore, such a data processing apparatus incorporates a high performance CPU, which consumes much power and generates a great amount of heat. Therefore, there have been devised various methods for radiating to the outside heat from a heat source such as a high performance CPU. Meanwhile, improvements have been made to such a high performance CPU itself in order to cope with heat generation; e.g., employment of a low-power consumption mode and employment of a design that enables low-voltage drive.
Means for circulating cooling air by use of a fan has been the most commonly used method for radiating to the outside heat from a heat source such as a high performance CPU that constitutes the above-mentioned data processing apparatus. That is, outside air is taken into a heat radiation device attached to a heat source, is passed through the interior of the heat radiation device, and is discharged to the outside of the heat radiation device. However, since the heat radiation apparatus itself has a reduced thickness, cooling air does not flow smoothly through the interior of the heat radiation device. Since the non-smooth flow of cooling air decreases the cooling efficiency of the heat radiation device, heat from the heat source cannot be effectively radiated to the outside. Further, since the cooling air flows through a limited narrow space within the heat radiation device, a portion of air to be discharged is not discharged from the heat radiation device. That is, a portion of air that must be discharged to the outside is again taken into the interior of the heat radiation device, thus further decreasing the cooling efficiency.
Cooling performance can be improved through an increase in the flow rate of cooling air. However, since this measure requires an increase in the size of a fan, the overall thickness of the heat radiation device or the data processing apparatus cannot be decreased. Practically, since a space for accommodating a large fan cannot be secured in a thin heat radiation device and a thin data processing apparatus, the above-described measure cannot be employed.
An object of the present invention is to provide a heat radiation device for a thin electronic apparatus which can improve cooling efficiency without rendering difficult decreasing the thickness of a data processing apparatus.